PROJECT SUMMARY/ABSTRACT The Data & Methods Core will provide cross-cutting expertise in data management and analysis methods. The Core comprises researchers with extensive experience with the data and methods involved in the Program Project. It will provide leadership on issues common to all projects, day-to-day direction in the management of complex data sets and analyses, and novel methods to advance the scientific goals of the Program Project. The Core has three primary aims. First, the Core will coordinate data resources, including acquiring, preparing, integrating, managing, and ensuring quality of the data needed for projects. Across projects, many data challenges can be solved once in the core rather than individually in each project, ensuring uniformity in approach to data issues and cost-effective use of Program Project resources. Second, the Core will provide general analytical expertise on Project analysis issues such as measure development, modeling techniques, economic theory, causal inference, and statistical inference. Applying expertise across the range of projects will enable investigators to identify cross-cutting issues and develop solutions that can be broadly applied. Third, the Core will develop and apply novel methods relevant to missing data and quasi-experimental designs. The methodological work will closely align with the research needs of the projects, enabling more robust and rigorous research conclusions. The Medicare program is vital to the health, welfare, and financial security of older adults and to the federal government's budget. This Program Project, with leadership and support from the Data & Methods Core, will conduct empirical analysis with broadly representative data, carefully specified measures of clinical quality and resource use, and rigorous statistical methods.